Every operating system ever created has its own set of features and drawbacks. Some operating systems may be full featured, with an extensive set of capabilities, while other operating systems may be leaner and capable of faster processing. Additionally, various applications may be written to be executed within one operating system but not another.
Many computer systems are designed to operate with a single operating system. Some computer systems execute additional operating systems using hypervisors, user mode, or other techniques to present a virtualized hardware platform to a guest operating systems. Such techniques add a layer of complexity and processing between the guest operating system and the hardware, adding to decreased performance of the guest operating system.